If you're specifically looking for a registration code solution due to a "hot" or urgent issue, providing more details about the error message you're receiving or the platform you're using could help in pinpointing a more accurate solution.

: If you have installed the game multiple times, you may hit a hidden activation cap. You must contact EA Support to request a manual activation limit reset for your specific key .

The "invalid registration code" or "activation limit" errors for Need for Speed: Undercover